Process of softening water.



UNITED STATES PATENT OFFICE.

HERlltllANN LEY, OF ELBERFELD, GERMANY, ASSIGNOR TO VEREINIGTE SEIDEN- FARBEREIEN C. A. LANGENBECK & I. P. LOHE, OF ELBERFELD, GERMANY, A

FIRM.

No Drawing.

To all whom 1' t may concern Be it known that I, HERMANN LEY, chemist, a subject of the King of Prussia, residing at No. 10 Gambrinusstrasse, Elberfeld, in the Kingdom of Prussia, German Empire, ha e invented a new and useful Improvement in Processes of Softening Vater.

It is known that the hardness, that is to say the lime and magnesium salts, can be withdrawn from a Water by causing the water to trickle or run over double silicates of alumina, whether, these be artificial or natural. The reaction consists in-the exchange of the alkali-metal bases, soda or potash, of the double silicate of alumina for these of the calcium and magnesium salts.

of the hard water. It is generally accepted that this property of softening a water helongs only to the double silicates of alumina, but I have observed that other silicates pos+ sess analogous properties. This discovery constitutes the basis of the present inven% tion. Y

When a water is mixed with a substance which is obtained by heating a solution of an alkali-metal silicate with a solution of a compound of an alkali-metal or alkalineeart metal, such as common salt, sulfate of soda or another salt, the production of which substances with the exception of those produced by the reaction of a solution of phosphate of soda with a solution of soda water glass described below is in itself known, and this mixture is shaken, it is found on testing the hardness of the water that this has been considerably diminished or eliminated by the treatment with the substance in question; the following experimental details confirm this.

1. 100 liters of a solution of phosphate of soda of 10 per cent. strength is mixed with 1 liter of soda water glass solution and the mixture is heated to boiling. The precipitate thus obtained is collected, washed with soft water until the alkaline reaction has disappeared, and is then dried at C. The comminuted product is sifted so as to produce a size of grain as uniform as possible. This constitutes a softening agent.

2. Another material for the same purpose is obtained by mixing 100 liters of a solution of sulfate of soda of 10 per cent. strength with 1 liter of soda-water glass solution and the mixture is heated. The precipitate produced is treated in manner Specification of Letters Patent.

Application filed November 24, 1913.

Patented Sept. 8, 1914.

Serial No. 802,647.

analogous to that described under 1. 100 grams of either of these products is charged into a suitable glass tube and Water of 9 hardness is allowed to trickle over the ma-.

terial at such a speed that in the course of an hour one liter of purified water is obtained.

The proportions given are selected because in practice 300 cubic meters of a water of 9 hardness are softened in 10 hours with about 3000 kilos of permutite. The 100 grams of softening material containing about 30 per cent. of moisture mustsoften 10 liters of water completely in 10 hours in order that the same effect may be obtained (b) The water filtered through the softening material obtained according to the prescription given under 2 showed the following results 0 of hardness after passage of litfilS of th e water I I U I H H 0 u u u I u u 16 u 0 u u u u u 18 u The silicate exhausted after repeated use recovered its original power of softening the water when it was regenerated with common salt in manner analogous to the treatment of double silicates of aluminium.

It has been found that in making a softening agent by heating an alkali-metal silicate solution with a solution of phosphate of soda an essentially higher yield of the agent is obtained as compared w1th that produced when other alkali-metal compounds, such as sodium chlorid, sodlum sulfate or sodium acetate are used, so that the use of phosphate of soda for maklng the softening agent is most suitable from the point of view of economy. For the purpose of comparison experiments were unu u i u n u I: u

u u u u u u u u u dertaken in which on the one hand a solu-.

tion of sodium sulfate, sodium chlorid or sodium acetate was added to the alkahmetal silicate solution for producing a prekilos of water. glasswere mixed with 100 liters of a neutral solution of the salt of 10 per cent. strength; 300-grams of precipitate were obtained corresponding with 7.5 per cent. of the water glass used. 3. 5 kilos of water glass were mixed with 100 liters of a neutral solution of the salt of 10 per cent. stren h; 400 grams of precipitate were obtaine corresponding with 8 per cent. of the water glass used.

'11. By addition of phosphate of soda to water glass-4. 3 kilos of water glass were mixed with 100 liters of phosphate of soda u 2. 4 kilos of water glass were mixed withsolution of 10 per cent. strength; 750 grams ofprecipitate were obtained corresponding with per cent. of the water glass used.

100 liters of phosphate of soda solution of 10 per cent..strength;,1050.grams of precipitate were obtained corresponding with 26 per cent. of thewater glass used. 3. 5 kilos of water glass were mixed with 100 liters of phosphate of soda solution of 10 per cent.

strength; 2300 grams of precipitate were obtained corresponding with 40 per cent. of the water glass used.

From the foregoing figures it follows clearly that the separation of the softening agent from the water glass by means of phosphate of soda solution is much more considerable than by means of the neutral salts hitherto used and this is of great advantage in a technical sense.

I wish it to be understood that for the purposes of this invention alkali-metal salts aria the equivalent .of alkaline-earth metal sa ts.

What I claim as m invention and desire.

to secure by Letters atent is 1. The process of softening water by treating it with a precipitate obtained by mixing a solution of hosphate of soda with a solution of an a1 ali metal silicate, the.

softening effect being obtained by an exchange of bases, substantially as set forth.

2. A process for making a water softening agent of the kind which acts by the ex change of bases, which process consists in.

mixing a solution of phosphate of soda with a solution of an alkali-metal silicate and separating the precipitate produced.

HERMANN LEY. 1.5.

' Witnesses:

- ALBERT Knnrna,

h R. LOHE. 

